Problem: Gabriela is 5 times as old as Emily and is also 20 years older than Emily. How old is Gabriela?
Explanation: We can use the given information to write down two equations that describe the ages of Gabriela and Emily. Let Gabriela's current age be $g$ and Emily's current age be $e$ $g = 5e$ $g = e + 20$ Now we have two independent equations, and we can solve for our two unknowns. One way to solve for $g$ is to solve the second equation for $e$ and substitute that value into the first equation. Solving our second equation for $e$ , we get: $e = g - 20$ . Substituting this into our first equation, we get the equation: $g = 5$ $(g - 20)$ which combines the information about $g$ from both of our original equations. Simplifying the right side of this equation, we get: $g = 5g - 100$ Solving for $g$ , we get: $4 g = 100$ $g = 25$.